Iray and hair - how to make it look good?

I have some success in Iray, concerning materials and skin. But one problem is hair. I always had problems with hair in Reality/Luxrender, and I have the same problems in Iray. How do you make hair look good/realistic in Iray? Are there some special settings to tace care of? Is there a dedicated hair shader for Iray? In my Iray renders hair always looks like plastic.

Comments

Turn up the bump (1 is a lower value in Iray than 3Delight). If the hair doesn't already have SubD, add it in the scene tab button and turn it up to 2 or so to make it look smoother and less jagged, too. You can also profitably fiddle with the gloss settings.

It worked in this case, I have only tried once, haha.
Apply the wax shader while pressing ctrl to retain the maps. Adjust the translucency stuff to your liking, I think I used 0.5, maybe lees for the base scalp (and can`t remember the correct name of the value, it`s all too new).

It worked in this case, I have only tried once, haha.
Apply the wax shader while pressing ctrl to retain the maps. Adjust the translucency stuff to your liking, I think I used 0.5, maybe lees for the base scalp (and can`t remember the correct name of the value, it`s all too new).

If that's the case, you can get the same result without using the wax shader by turning up the SSS and translucency and giving them a neutral transmitted color (white or gray). It will slow render but it will get that "light shining through the hair" effect.

Actually I just found out how to get the translucency options, I`m setting it to 0.5 with the same color of the hair. No SSS. Worked with the hair I was testing it. If it works for other hairs too, I`ll share a preset.

Actually I just found out how to get the translucency options, I`m setting it to 0.5 with the same color of the hair. No SSS. Worked with the hair I was testing it. If it works for other hairs too, I`ll share a preset.

My attempts at trying to make a better hairstyle didn't quite go so well when trying Hellboy's wax preset. The hair went from blonde to black and my attempts to make it less black made it more of a muddy brown.

So, I started from scratch with this one. I set the base colour to scatter and transmit, used a small amount of translucency (set to 0.2) on everything except the scalp, raised the gloss a little bit and added a light behind the young miss to get a nice halo effect. The only other lighting is a HDR environment.

Still needs tweaking, but it's a work in progress. I'll see if I can come up with anything better as I play around more.

Hair has been a challenge for me as well. Some hair looks good, some hair looks awful and it seems to come down to how it's made and what trans maps I have to work with.

...yeah, Osean Hair is one that doesn't seem to do well in Iray. Looks way too thin almost to the point of making it look like the character is suffering from early stages of radioactive exposure.

Fig. 1. Iray

Fig. 2. 3DL

(for some reason the order of the images were flipped by the forum software)

I've had a similar issue with Lanny hair. From the sides it looks alright but from straight on it looks all wispy like the person is losing big chunks of hair. I know it has to do with the opacity map and I tried tweaking it in photoshop and that didn't help. Leaving it out means you can tell the hair is basically rectangles laid on each other.

On the Lanny hair if I turn it off you can see the rectangles the hair is made of. If I give it even a tiny bit, it looks thin from the front like the hair he showed. I'll do a render in a bit to show you.

Just removed off the opacity map and it looks like she's waring one of those string mop heads

Exactly. I know my issue with the Lanny hair comes down to the Opacity map but my skills aren't up to making whatever change I need to make in photoshop. I think it comes down to 3Delight vs Iray just uses opacity maps differently.

I found a clue as to what may be going on with the uber-transparent hair.

Looking at the Luxus wiki, there was a line stating that transparency maps were no longer being auto-corrected for gamma.

So, you may want to try manually tweaking/shutting off the gamma correction on the transparency maps.

The results shown are consistent with the maps being grey instead of black and white. On a transparency map grey basically equals translucency...and with 'natural' translucency the 'extra' from the grey areas on the map will make it almost 'not there', it's so translucent/transparent...

I found a clue as to what may be going on with the uber-transparent hair.

Looking at the Luxus wiki, there was a line stating that transparency maps were no longer being auto-corrected for gamma.

So, you may want to try manually tweaking/shutting off the gamma correction on the transparency maps.

The results shown are consistent with the maps being grey instead of black and white. On a transparency map grey basically equals translucency...and with 'natural' translucency the 'extra' from the grey areas on the map will make it almost 'not there', it's so translucent/transparent...

I stuck one of the transmaps in photoshop and made it pure black and white by tweaking the contrast. I'll let you know how it turns out in a bit.

A downside (if you can call it that) of unbiased rendering is that it's so physically accurate it will make all the 'weak' parts of your render look less real. There are a very few transmap prop/cr2 hairstyles that can look 'meh ok' in unbiased rendering (in certain lighting and at certain angles), but the vast majority are going to look like what they are, a helmet with hair painted on (ie, not good). And if you want to do unbiased animation, you'd better have a super-great-detailed hair prop with tons and tons of morphs painstakenly dialed for each frame, or else it's going to look pretty 'fakey-fake'.

I use TheaRender, Octane, and Luxus, and it's been a problem for me for a while, and is something I think anyone who renders unbiased has run into and struggled with.

So rather than make a suggestion to do a little tweaking to make the prop hair look slightly less terrible (which bravo if you can achieve that), I think there's a whole alternative way of going about hair, which is to just move to strand-based dynamic hair instead.

I'm not sure if Look At My Hair or Garibaldi Hair can be animated with scene forces, but even if not, for still renders either of them would be a much more ideal solution than nearly any transmap hairprop out there. I don't know if Iray will recognize and render them (so much the better if it does) but even if not, simply doing a render pass of the hair and it's shadow and combining that in post with the Iray unbiased render should give extremely realistic hair.

I recently did this as a proof of concept of putting Carrara hair into an Octane animation; it's a silly little animation that serves no purpose and isn't all that great in any area, but just proves the point that if you want to you can indeed put dynamic hair into an unbiased render.

I should also add that Blender Cycles can render Blender dynamic hair too.

Just an alternate solution for the hair problem in unbiased rendering.

They can't, or I'd never use anything else. The difficulty of getting them to behave as if they're affected by gravity is what makes using them so hard to begin with.

But it's early days yet. Iray is still in beta. I'm hoping we'll eventually get real dynamic cloth and hair to use with this engine - surely DAZ now has more motivation than ever before to pursue that.

I'm realizing that most facial hair, I'm likely going to be forced to use LAMH, because the one flexible facial hair thing I have doesn't really morph with expressions (which is a problem even in 3Delight).

Thankfully, I don't do animations and the number of facial hairs shouldn't utterly shred my machine.